A systematic study of mobility performances and Bias Temperature Instability (BTI) reliability was done on a large variety of advanced dielectric stacks. We clearly demonstrate that mobility performances and NBTI reliability are strongly correlated and that they are affected by the diffusion of nitrogen species N at the Si interface. Reducing the metal gate thickness favors the reduction of mobility degradations and NBTI, but, also strongly enhances PBTI, due to a complex set of reactions in the gate oxide. An optimum gate thickness must be found to obtain an acceptable trade off between device performance and reliability requirements.
26 Apr 2009
2009 IEEE International Reliability Physics Symposium